1. Field of the Invention
The present invention relates to an in-cylinder injection type multicylinder internal combustion engine for uneven interval firing, including a plurality of air-fuel mixture injection valves for directly injecting an air-fuel mixture into a combustion chamber of each cylinder. The air-fuel mixture injection valves is mounted on a multicylinder engine body and each having a fuel injection valve for injecting fuel and an air injection valve for injecting a mixture of the fuel injected from fuel injection valve and injection air. An air pump is actuatable by power transmitted from a crankshaft for discharging compressed air as the injection air. The air pump is connected in common to the air-fuel mixture injection valves.
2. Description of Background Art
An in-cylinder injection type internal combustion engine is known in which an air-fuel mixture injection valve is provided for directly injecting an air-fuel mixture into a combustion chamber. The air-fuel mixture injection valve includes a fuel injection valve for injecting fuel and an air injection valve for injecting a mixture of the fuel injected from fuel injection valve and injection air that are mounted in a cylinder head. See, for example Japanese Patent No. 4135912.
Japanese Patent No. 4135912 discloses the injection timings of a fuel injection valve and an air injection valve with the valves constructing the air-fuel mixture injection valve in a single-cylinder internal combustion engine. If the injection timings are applied to a multicylinder internal combustion engine for uneven interval firing, then the discharge timing of the air pump tends to overlap the injection timing of the fuel injection valve or the air injection valve of either one of the cylinders, possibly causing a change in the injection pressure of the fuel injection valve or the air injection valve.